Actually my piont was that I could Identify the bbs I used and had success with. Perhaps the jamming is due to another brand of bb walmart stocks (lasersoft). I have used the arctic white in my stock guns that shoot under 350 fps with success. They are Bios and do not have a polished surface.
I have purchased Bios (0.20g) from my local shop that are made by cybergun as well, they are green with no polish and the same count (5000) at double the price. They say on the package guaranteed not to jam.
To this date I have not seen them perform any different than the arctic white from walmart (that is when I can see them). Tested today alongside the arctic white and velocity arms 0.20g polished at 60ft. Similar operation in its accuracy (same groupings), only difference I noticed was that the Bios had grouped a little higher. Either I was positioned a bit off or perhaps the bios get gripped by the hop-up differently.
On a side note, my 400fps rifle only gets fed 5.97mm +/- 0.001 0.25g bbs just to ensure it will perform properly. I use the walmarts when under 350fps and stock barrel. It is important to give your investment the best in parts and ammo to keep repairs from being frequent.